Domestic appliance



Oct. 2, 1956 G. c. PEARCE ETAL DOMESTIC APPLIANCE 2 Sheets-Sheet 1 Filed May 14, 1953 O= OFF H=HlGHfS=SiMMER L=LOW MH=MED. HIGH M MEDIUM ML= MED. LOW

Their Affomey Oct. 2, 1956 G. c. PEARCE ET AL DOMESTIC APPLIANCE 2 Sheets-Sheet 2 Filed May 14, 1953 and m w mmm w mmd W N m CH. f es mm m T WM Y B DOMESTIC APPLIANCE George C. Pearce and James H. Nellis, Dayton, Ohio, assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application May 14, 1953, Serial No. 355,058

1 Claim. (Cl. 200-6) This invention relates to a domestic appliance and more particularly to switches and their manual control arrangements.

Some switches are frequently used. This is especially true of switches for electric ranges. It is desirable that they be easily and quickly manipulated without confusion by a limited turning of one hand without looking at the switch knob or dial. It is an object of my invention to provide a switch in which a plurality of switch stations can be reached with a minimum of turning of the knob or wrist.

It is another object of my invention to provide a switch which can be returned to off or circuit breaking position with a minimum of effort.

It is another object of my invention to provide an ornamental knob with an improved indicating arrangement.

These objects are attained in the form of the invention shown by providing a switch arrangement which connects two heating elements into six different circuit arrangements with an Edison 3-wire supply source to provide six different heating rates. The switch arrangement is located so that the circuit breaking or off position is between two sets of three heats so that all heats are readily accessible from the off position. A manipulating knob is connected to the switch arrangement in such a way that by turning the knob less than 90 in either direction all of the different heats for switch arrangements can be obtained. The knob is connected by a keyed hollow sleeve and gearing with the switch arrangement and with a resilient detent means which resiliently holds the knob and the switch arrangement in any of the indicated heat positions.

Within this sleeve there is provided an element of translucent material projecting from the face of the knob. An indicating light is provided at the rear of this translucent element which is controlled by a switch means coordinated with the switch arrangement to indicate when any heating circuit is energized.

The device is provided with a spring arrangement which is wound up in either direction as the knob is turned away from the off or circuit breaking position. The translucent element may be operated as a pushbutton to release the detent or stationing device to free the knob and the switch arrangement for its return to the off or circuit breaking position under the force provided by either of the springs of the spring arrangement.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the invention is clearly shown.

In the drawings:

Figure 1 is a diagrammatic perspective view and wiring diagram of a knob and switch control for a surface heater embodying one form of my invention;

Figure 2 is a vertical sectional view taken along the line 2-2 of Figure 1;

Figure 3 is a fragmentary enlarged perspective view nitecl States Patent O "ice of a portion of Figure 1 taken along the section line 33 of Figure 2; and

Figure 4 is a sectional view taken along the line 4-4 of Figure 2.

Referring now to the drawings and more particularly to Figure 1 there is shown a portion 20 of a range top and front of a domestic electric range. Indicated as electrical resistance in the wiring diagram are the elements 22 and 24 of a surface heating unit of an electric range. The one end of each of these elements 22 and 24 is connected to the conductor 26 which in turn is connected to the spring blade 28 of a single throw switch. This blade 28 is provided with a movable contact 30 at its lower end which cooperates with a stationary contact 32. The switch blade 28 is provided with a V-shaped cam follower adapted to cooperate with the switch cam 34 fixed to the rotary shaft 36. The cam 34 has raised portions in the sectors marked 0, ML, and S. When these portions engage the cam follower the contact 30 is held in the open circuit position. In the sectors MH, M, L, and H, are low portions of the cam which when engaged by the cam follower will permit the movable contact to engage the stationary contact 32 under the spring force inherent in the spring blade 28.

The second or left end of the heating element 24 is connected by the conductor 38 to the movable double throw switch spring blade 40 provided with a double contact 42 at its lower end which is moved by the cam 44 into engagement with either of the stationary contacts 46 or 50. For this purpose the cam 44 has raised portions in the sectors marked MH, H, and S which when they engage the V-shaped follower upon the switch blade 40 are adapted to move and hold the movable contact 42 into engagement with the stationary contact 46. The cam 44 has portions of intermediate radius in the sectors marked 0, L and M which when engaged by the V-shaped cam follower of the switch blade 40 are adapted to hold the movable contact 42 in mid position out of engagement with either of the stationary contacts 46 or 50. The cam 44 also has a sector ML of lesser radius which when engaged by the follower of the switch blade 40 permits the movable contact 42 to be moved by the spring force inherent in the spring blade 40 into engagement with the stationary contact 50. This cam is fixed to the shaft 36 and oriented so that its sectors maintain contact with their respective cam follower in the same relationship at all times as does the cam 34.

The second or left end of the heating element 22 is connected by the conductor 52 to the movable double throw switch blade 54 having a movable double contact 56 at its lower end which is adapted to move between and engage either of the stationary contacts 58 or 60. This movement is performed by the third cam 62 likewise fixed to the rotatable shaft 36 and oriented so that its sectors bear the same relationship to the V- shaped cam follower provided on the switch blade 54 as the sectors and cam followers of the cams 44 and 34. The cam 62 has a sector 0 of intermediate radius which holds the double contact 56 at an intermediate point between the stationary contacts 58 and 60. The sectors marked MH, S and L are of larger radius and when in contact with the cam follower of the movable switch blade 54 hold the double contact 56 in contact with the stationary contact 58. The sectors M, ML and H have shorter radius so that the spring force inherent in the switch blade 54 when the cam follower is in contact with the surfaces of these sectors will carry the double contact 56 into engagement with the stationary contact 6%).

The circuit is completed by conductors 64 connecting the stationary contacts 32 and 50 with the supply conductor 66. There are also provided conductors 68 connecting the stationary contacts 46 and 60 with the supply conductor 70. The stationary contact 58 is connected by the conductor 72 to the neutral supply conductor 74. The conductors 66 and 70 are the live or red and black conductors of the 3- wire Edison-type supply conductor While the conductor 74 is the white or neutral conductor.

The front end of the shaft 36 is provided with a small gear 76 which meshes with a large gear 78 which is approximately twice the diameter of the small gear 76. This gear 73 is keyed to the hollow shaft or sleeve 80 provided with a keyway extending substantially from end to end. The front end of this hollow shaft 80 is provided with a hollow manipulating knob 82 having a pointer cooperating with the dial 84 on the front of the range top portion 20. This dial 84 has a legend in the upper central portion indicating the off or circuit breaking position. Extending in the clockwise direction at intervals of less than 30 are the legends H, S and L corresponding to the high, simmer and low heats provided by the switch arrangement. Extending counterclockwise at intervals of less than 30 are the legends MH, M and -ML in order corresponding to the heats medium-high, medium, and medium-low provided by the switch arrangement. Thus, with a movement of the knob 82 of less than 90 in either direction, any of the heats may be obtained which are provided by the switch arrangement in 360 of rotation. This makes manipulation easy and more rapid.

Fastened to the rear face of the front portion of the range top portion is a heavy sheet metal frame member 86 having a centrally located flanged aperture 88 providing a bearing for the shaft 81). The rear end of the shaft 80 is provided with a series of saw-shaped teeth 99 so located as to resiliently hold the shaft 80 and the knob 82 in any of the positions designated by the legends on the dial 84. Cooperating with the teeth 90 on the end of the shaft 80 is a detent ring 92 having teeth complementary to the teeth 90. This ring 92 is welded to the detent plate 94. The resilient force is provided by the coil springs 96 and 98 which connect the upper and lower edges of the plate 94 with the upper and lower portions of the frame 86 as indicated in Figures 1 and 2.

According to the present invention, the shaft 80 is provided with an ingenious arrangement for quickly turning the knob shaft and switch arrangement to the off or circuit breaking position. Referring now more particularly to Figures 2 and 3 there is keyed to the shaft a double armed two-way lost motion member 121 having a rearwardly extending projection 123 and 125 on each arm. Back of this double lost motion member is a counterclockwise spring arm 127 having its hub portion rotatably mounted upon the shaft 80. This counterclockwise arm 127 has its end portion bent forwardly and connected to the upper end of a coil spring 130. The lower end of the spring 130 is connected to the projection 131 provided upon the frame 86. The arm 127 extends over and is substantially in contact with the projection 123. It also extends over the platform 133 provided by the frame 86 and is normally held in contact with the platform 133 by the coil spring 130.

Back of the counterclockwise arm 127 is a clockwise arm 129 having a hub portion likewise rotatably mounted upon the shaft 80. The end of the arm 129 is bent forwardly and connected to the upper end of a coil spring 135 the lower end of which is connected to the projection 137 of the frame 86. The coil spring 137 normally holds the end portion of the arm in engagement with the platform 139 provided by the frame 86. The detent springs 96 and 98 are made sufficiently strong as compared to the effective force of the rotating springs 13% and 135 that the detent mechanism will hold the knob and the switch mechanism in any one of the positions designated on the dial 84. Therefore when the knob 82 is turned clockwise the projection 123 will engage and lift the arm 127 away from the platform 133 and carry the arm along with the shaft 80 in its rotation.

Also if the knob 82 is turned in a counterclockwise direction to any of the positions indicated on the dial 84, the projection 125 will engage the bottom of the arm 129 and carry the arm 129 with it in synchronism of rotation of the shaft 80.

The center of the hollow shaft is filled by a push rod or button 141 which is slidably mounted therein. The front end of this rod is provided with circular grooves. The rod is preferably made of some suitable transparent light carrying material such as polymethyl methacrylate or polystyrene. At its rear end it is provided with a shoulder 143 which bears against the detent plate 94 as shown in Figure 2. At the side of the shoulder 143 the push rod 141 is provided with a bearing in the centrally located aperture of the detent plate 94 and on the opposite side is provided with a retaining ring 145. When the front end of the rod 141 is pushed in, it moves the detent plate 94 rearwardly to wholly or partially disengage the teeth and the ring 92 so as to free the hollow shaft or rod 80 for rotation under the force provided by whichever of the springs or which may be stretched or activated by the rotation of the knob 82 away from the off position. When so freed the shaft 80 and the knob 82 as well as the gears and the switch cams will be turned quickly to the off position and stop there by the engagement of the ends of either of the arms 127 or 129 with either of the platforms 133 or 139. This stations the stopping of the knob 82 and the switches in the O or off position whenever there is depressed the push-button end of the rod 141.

The rear end 147 of the rod 141 is made concave. Located directly behind this concave surface is an'indieating light 149. This indicating light 149 is controlled by a separate switch mechanism. The indicating light 149 has one of its terminals by the conductor 151 to the black supply conductor 70. Its second terminal is connected by the conductor 153 with a stationary contact 155 (see Figures 2 and 4) which is connected to but insulated from the detent plate 94. The detent plate 94 preferably is made of electrical insulating material. The detent plate 94 also carries a second contact 157 connected by the conductor 159 with the neutral conductor 74.

These contacts 155 and 157 cooperate with a contact ring 161 fastened to an insulating ring 163. This insulating ring 163 is spring-pressed by the coaxially located coil spring 165 rearwardly to keep the contact r 1g 161 in engagement with the stationary contacts and 157. In the off position the contact ring 161 is provided with a window 167 (see Figure 4) located in alignment with the contact 155 to prevent contact between the contact 155 and the contact ring 161 to insure that the circuit comprising the conductor 159, 153 and 151 as well as the indicating light 149 is kept broken. When the knob 82 is moved away from the off position in either direction the window 167 will move away from the contact and permit the contact 155 to contact the ring This ring 161 will close the circuit by connecting the contacts 155 and 157 to energize the light 145. The contact ring 161 is fastened to the insulating ring 163 by four cars 1169 which are bent through four corresponding notches in the ring 163 and clamped to the opposite side of the ring 163.

The shaft 80 may have an integral connection with the knob 82. This shaft 80 may be retained in the bearing in the frame 86 by the retaining ring 171 which retains a washer 174 in contact with the rear face of the frame 86. The frame 86 has four rearwardly extending projections 173 which extend on either side of the upper and lower spring mounting ears 175 upon the detent plate 94 to prevent the rotation of the detent plate 94 without limiting its axial movement. The double arme member 121 as well as the spring biased arms 127 and 129 are held in proper position by a coil spring 175 surrounding the shaft 80 and extending between the member 121 and the front wall of the range top portion 20.

Thus I have provided an arrangement whereby in less than a 90 movement of the knob in either direction from the off position, all of the selective heats can be obtained. Also the combined illuminating and push-button arrangement indicates the energization and deenergization of the heating units and provides a means for quickly returning the switch arrangement to the off or circuit breaking position without the necessity of forceably returning the knob to the off position.

In accordance with the provisions of Rule 78a, reference is made to the following prior filed application, S. N. 7,882 filed February 12, 1948, issued as Patent No. 2,635,640 to James H. Nellis on April 21, 1953.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted as may come within the scope of the claim which follows.

What is claimed is as follows:

A control including switch means having a plurality of circuit completing positions and a circuit breaking position, means for biasing said switch means into said circuit breaking position, manipulating means including a hollow shaft for moving said switch means from one position to another, resilient detent means cooperating with said hollow shaft and having suflicient holding force to resiliently hold said switch means in any of said positions, and means including a transparent light transmitting push button rod extending through said hollow shaft for releasing said detent means to cause said biasing means to move said switch means into said circuit breaking position, said push button rod being translucent and having an inner concealed portion extending through said hollow shaft and an outer exposed portion at each end of said hollow shaft, an indicating light located outside of said hollow shaft adjacent one of said outer exposed portions, a second switch means being provided with a first contact means connected to said detent means and a second contact means connected to and rotatable with said hollow shaft for energizing said light in said circuit completing positions and for deenergizing said light in said circuit breaking position.

References Cited in the file of this patent UNITED STATES PATENTS 969,055 Hammond Aug. 30, 1910 1,766,658 Leake June 24, 1930 2,305,185 Merkel Dec. 15, 1942 2,404,940 Beal July 30, 1946 2,449,213 Fredrick Sept. 14, 1948 2,462,594 Beal Feb. 22, 1949 2,491,168 Dusek Dec. 13, 1949 

